This invention was made with Government support under Contract No. F04701-85-C-0038 awarded by U.S. Air Force Systems Command. The Government has certain rights in this invention.
This invention relates to feedback control loops and more specifically to accurately tracking input signals with a feedback control loop.
A wide variety of signals may be readily processed using existing feed back control loop techniques. In tracking any given signal with prior art feedback control loops, instability difficulties may result from an uncontrollable gain in the feedback control loop, thereby diminishing the effectiveness of further signal processing.
Prior art methods of compensating for this problem focus upon the use of limiter devices with preset values for controlling the feedback control loop response to signal gain. The effect of the use of limiters is to cyclically drive the signal from a maximum value to a minimum value back to a maximum value and so on. This bouncing of the signal from a high to low value maintains the signal within a given value window, however the feedback control loop does not actually respond to signal fluctuations.
The present invention effectively replaces the hard limit values with a variable attenuator having the ability to respond to detected gain drift.